Same-sex marriage survey hurtful: Kirby

Former High Court judge Michael Kirby has criticised the postal survey on same-sex marriage.

Former High Court judge Michael Kirby has weighed into the same-sex marriage debate, describing the postal survey as "hurtful".

Speaking at a graduation ceremony at the University of Adelaide on Wednesday, Mr Kirby says the survey shows once again that gay Australians are singled out for discrimination and unequal treatment under the law.

"To submit the rights of a minority of citizens of this country to the voting decision of a majority of others as a precondition to the mere possibility of having the issue considered in the normal way in parliament is very hurtful," he told the ceremony on Wednesday.